Why Does Time Decay Accelerate in the Final Month before Expiration?

The acceleration of time decay in the final month is due to the non-linear nature of an option's time value. As the time horizon shortens, the probability distribution of the underlying asset's price narrows significantly.

The remaining time value, which represents the uncertainty, must be absorbed rapidly into the option's price before it reaches zero at expiration. This compression causes Theta's absolute value to spike.